Maltodextrins from amylose

Comparison of Experimental and Theoretical Yields of Maltodextrins from Amylose ... 

Maltodextrins (DE below 20) have compositions that reflect the nature of the starch used. This depends on the amylose/amy-lopectin ratio of the starch. A maltodextrin with DE 12 shows retrogradation in solution, producing cloudiness. A maltodextrin from waxy com at the same DE does not show retrogradation because of the higher level of a-1, 6 branches. As the DE decreases, the differences become more pronounced. A variety of maltodextrins with different functional properties, such as gel formation, can be... 

Maltodextrins a-amylase action on, 315 from amylose, 318,321,323 salivary a-amylase action on, 319 Maltose, /3-, mutarotation of, 23 —, l,2,2, 3,3, 4 -hexa-0-acetyl-6,6 -di-0-p-tolylsulfonyl-/3-, 241 Maltoside, methyl 6,6 -di-0-p-tolylsulfo-nyl-/3-, 241 Mannans... 

Earlier studies on the properties of phosphorylases isolated from various sources have indicated that their subunits are similar in size with about 100,000 daltons.15-17 The reaction proceeds in a rapid equilibrium random Bi-Bi mechanism as has been shown by kinetic studies with rabbit skeletal muscle phosphorylases a18-20 and b,21,22 rabbit liver enzyme,23 potato tuber enzyme,24 and the enzyme from E. coli.25) In contrast, the substrate specificities for various glucans differ considerably depending on the enzyme sources. The rabbit muscle enzyme has high affinity for branched glucans such as glycogen and amylopectin but low affinity for amylose and maltodextrin.26,27 The potato tuber enzyme can act on amylose, amylopectin, and maltodextrin but only poorly on glycogen,28,29 while the E. coli enzyme shows high affinity for maltodextrin.10 ... 

Protein (Total) Not more than 0.5%, except not more than 1.0% in Maltodextrins produced from high-amylose starches. Residue on Ignition Not more than 0.5%. 

It is the amylose component of starch that gives the blue color when KI/I2 solution is added. To study the iodine-iodide color of amyloses of different d.p. values, maltodextrin-amylose molecules, with various avg. d.p. values from 6 to 568 were prepared by Bailey and Whelan [62], using phosphorylase, a-D-glucopyranosyl-1-phosphate, and maltohexaose. The colors of the various sized maltodextrins (1 mg) were observed when 10 1 (w/w) KI/I2 solution was added. The first color to be observed was faint red for avg. d.p. 12 a red-purple color was observed for avg. d.p. 31 a purple color was observed for avg. d.p. 40 and a blue color was observed for avg. d.p. 45. The increase in the blue value was linear as a function of avg. d.p. up to avg. d.p. 60 the absorbance at 645 nm then slowly increased and reached a maximum at avg. d.p. of 400. The intensity of the iodine/iodide color in the low molecular weight range was dependent on the concentration of the iodine. When the concentration of the iodine was increased 10-fold, the intensity was increased 50% [62]. 

The formation of amylopectin occurs through the action of starch branching enzyme on mal-todextrins and/or amylose to form the a-(1 6) branch linkage. Amylose or maltodextrins can be used as the substrates, but the amylose must be at a concentration of 1 mg/mL or less, as higher concentrations leads to the precipitation (retrogradation) of amylose from solution. 

The use of amylose gel cross-linked by epichlorohydrin for affinity chromatography of extracellular isoamylase of Pseudomonas amyloderamosa has been studied. The isoamylase was adsorbed well on the amylose gel and was eluted specifically with maltodextrin. The eluted enzyme was precipitated with ammonium sulphate to remove maltodextrin, and then the solution of the precipitate was dialysed and concentrated by vacuum filtration. By this procedure 96 mg of the enzyme were purified to homogeneity from 20 1 of culture broth in about 70% yield. 

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